1. Field of the Invention
The present invention relates to an energy conversion apparatus of mutually converting an electric energy and a mechanical energy.
2. Description of the Related Art
An exemplary energy conversion apparatus of mutually converting an electric energy and a mechanical energy is a speaker or a microphone. In the speaker, a coil arranged in proximity to a permanent magnet is vibrated by an electromagnetic force and a diaphragm fixed to the coil causes air to vibrate so as to generate sound waves. On the other hand, in the microphone, the diaphragm is vibrated by the sound waves so that an electric current flows through a coil integrated (interlocking) with the diaphragm by a function of electromagnetic induction.
Conventionally, a cone diaphragm is frequently used for a speaker. In recent years, a thin speaker (a so-called flat speaker) using a plate diaphragm has been attracting public attention (see, for example, Patent Document 1).
Although the above flat speaker is highly valuable depending on a usage, there is a restriction in an installation location and an energy conversion efficiency is not always sufficient.
Patent Document 1: Japanese Patent No. 5262599